A variety of different needle guards have been developed or proposed to protect, i.e., to enclose or otherwise shield, sharp needle tips in recognition of the need to reduce or eliminate accidental needle-sticks. Some needle guards include a housing to enclose essentially the entire needle shaft and needle tip, such as the PROTECTIV Safety I.V. Catheter being marketed by Medex, Inc., the assignee of the parent application hereof (which subsequently merged with and into Smiths Medical ASD, Inc.). Others include a clip that moves along the needle shaft to enclose the tip after use, such as shown in U.S. Pat. No. 6,652,486. Still other needle guards provide a housing that moves along the needle shaft with an enclosed active element to secure a distal portion of the needle with the tip inside the housing. Particularly advantageous forms of these needle guards include as the active element a canted-plate as described in U.S. Pat. No. 5,322,517.
In the canted-plate device of the '517 patent, a housing is provided through which the needle passes. Within the housing, a canting plate is defined by a wall with an aperture to slidably receive the needle shaft therethrough in a first state but which grips or bites into the needle shaft in a second, tilted or canted state relative to the first position. A second wall is connected to the first wall via an intermediate wall to define a generally rigid, single piece clip. The second wall includes a portion to ride along the needle shaft to hold the clip in the first state. When the needle tip is pulled into the housing and past the second wall portion, the clip can tilt into the second state such that the canting plate grips the needle shaft to prevent the needle from being pulled any further. Also, the second wall blocks the needle tip to prevent the needle from being pushed back out of the housing. A biasing spring is provided, bearing against the first wall, to urge the clip to the second state. The clip second and intermediate walls are to one side of the needle shaft in the first state with the spring to the other side of the needle shaft. While the clip design of the '517 patent has many advantages, further improvements and enhancements are desired.
One attempt to build upon the clip design of the '517 patent is shown in U.S. Pat. No. 6,280,419 which includes features intended to allow use of the clip with a guide wire. What is understood to be a commercial embodiment of the device of the '419 patent is the Arrow Radial Artery Catheterization device. The commercial embodiment is believed to have drawbacks including that its design also imposes significant drag force on the needle shaft, which make it difficult and undesirable to use.
Further, some needle guards are intended to be used with catheter assemblies. With such needle guards, it is advantageous to have a portion of the needle guard hold to the catheter hub while the needle projects out of the catheter tube, but to thereafter allow for ready removal of the needle guard upon withdrawal of the needle to the tip-protected position. One proposal is to provide a nose section of the needle guard with a pair of cooperating members extending from the needle guard housing. The cooperating members are sized to fit within the catheter hub and to normally define a passageway between the members, which is sized to slidably receive a needle shaft therethrough. One or both of the members has a detent at its distal end receivable in a respective radially outwardly extending recess formed in the interior wall of the catheter hub. The detent gives the member(s) the appearance of a duckbill. As will be appreciated, at least the distal portion of the catheter hub interior surface is tapered to female luer standards. The recess will be distal of the luer tapered surface and, when in the catheter hub, the detent(s) normally fit within the recess. When the needle shaft is removed from the passageway, one or both of the duckbill members is able to easily flex such that a slight tug on the housing causes the duckbill to yield against the recess allowing the needle guard to begin to come away from the catheter hub. But when the needle shaft is present, flexing of the members is limited such that the holding force is very high. The detents define an outer diameter of the duckbills sized to fit within the radially outwardly extending recesses. The inner diameter of the luer tapered surface, however, is smaller over a significant portion of its distal extent than the duckbill outer diameter. As a consequence, the duckbill members will remain flexed and will drag or scrape against the catheter hub interior surface during continued removal, which results in a feel and higher removal forces than might be desired by the medical practitioner.
The Arrow Radial Artery Catheterization device is an example of a duckbill design. But, the needle guard housing thereof cannot rotate relative to the catheter hub. Each duckbill detent has its own, limited circumferential length recess in the catheter hub, which thus holds the duckbill against rotation. It is often desirable to be able to rotate the needle guard housing relative to the catheter hub. As an example, it may be useful to rotate the components to thread the catheter tube into the patient. One proposed solution is to provide a continuous radially outwardly extending annular groove in the catheter hub such that the duckbill detent(s) may rotate therein as discussed in U.S. Pat. No. 6,221,047. But, in addition to the scraping problems mentioned above, a complete circumferential annular groove or recess in the catheter hub is believed to present manufacturing and product performance issues. Even one of the named inventors of the aforementioned '047 patent seemingly recognized the latter problem, and so subsequently proposed to go with the limited length recess such that the detent(s) would be inhibited from rotation within the catheter hub as discussed in U.S. Pat. No. 6,689,102. There is thus still a need for a viable rotatable solution for the duckbill, as well as a need to reduce or eliminate the problem produced by the scraping of the detents with the inner surface of the catheter hub during removal.